Half-duplex telegraph repeater



2 SI-IEETSSl-IEET 1 POLAR/ZED M in" M POLAR/ZED W. T. REA

HALF-DUPLEX TELEGRAPH REPEATER azcrnomc REGEN. REPEATER Sept. 30, 1952Filed Oct. 25, 1949 POLAR/IEO 0 E a R A I- a P POLAR/ZED 26/ REGEN.REPEAT-ER LECTRON/C FIG. 2

FLIP-FLOP POUR/ZED POLAR/ZED Sept. 30, 1952 w. T. REA 2,612,561

HALF-DUPLEX TELEGRAPH REPEATER Filed Oct. 25. 1949 2 SHEETS-Sl-IEET 2FIG. 3

JW g 309% in;

l s M 314 .9/5 403 3 S M L L ELECTRON/C REGEN.

L 5 REPEATER F I -FL 0/ i g 34a i asa- T m SEND E. SEND "Z M 339 3/3 338all 340 M By W. [REA ATTOQNE V Patented Sept. 30,1952 ,7

s PATENT OFFICE 2,612,561 HALF-DUPLEX TELEGRAPH REPEATER Wilton T. Rea,Manhasset, N. Y., assignor to Bell Telephone Laboratories, Incorporated,New

York, N. Y., a corporation of New York Application October 25, 1949,Serial No. 123,365

I 7 Claims.

This invention relates to an improvement in telegraph repeater systemsand more particularly to a telegraph repeater system in which a onewayregenerative repeater is arranged to serve for two-way half-duplexservice."

. An object of the invention is the improvement of telegraph repeatersystems.

A-feature of the invention is an arrangement whereby two telegraphrepeaters employed in half-duplex service may be interconnected in sucha manner that only a single regenerative repeater in common is requiredto' serve for both directions of transmission instead of an individualregenerative repeater for each direction.

The invention may be understood from the following description when readwith reference to the accompanying drawings in which preferredembodiments of the invention are presently incorporated. It is to beunderstood, however, that the invention may be incorporated in otherembodiments which will be readily suggested to thos'eskilled in the artby the present disclosure.

' In the drawings: Fig. 1 shows a system having two telegraph repeaterseach having an individual receiving leg and anindividual sending leg,which legs are interconnected through what corresponds to a common hubinthe usual hub telegraph repeater concentration, and in which system asingle regenerative repeater in common serves the two direc- I tions;andr A Figs-2 and 3 show other embodiments of the invention. I 1 Refernow to Fig. 1 which shows a first, or west, telegraph repeater at theleft,-connected to a second, or east, telegraph repeater at the rightthrough a hub or common branch, which corresponds to the hub of atypical hub repeater concentration, in the middle of the figure. Thewest repeater has a west receiving relay WR and a west sending relay WSconnected by means of a receiving leg l'anda sending leg 2 respectivelyto the common branch 3. The east repeater has an east receiving relay ERand an east sending relay ESv connected by means of a receiving leg 4and a sending'leg 5 respectively to the common branch 3. The commonbranch 3 includes an electronic regenerative repeater, well known in theart, which receives attenuated, distorted signalsand regenerates, orretimes and reshapes them and retransmits them. The sensing of thesignals,'that is, the determination of whether they be marking orspacing, is delayed until the middle portion of each element is beingreceived,

before they. are regenerated and retransmitted,

which results in a delay of approximately onehalf the duration-of eachsignal element between reception and retransmission, as well understoodin the art. The regenerated signals pass through resistance 25 in thecommonbranch and are impressed on the grid of vacuum tube triode 1, thecathode ofwhich is connected to ground. The hub or common branch may beconsidered as separable into a receiving hub and a sending hub. Thereceiving hub comprises the connections between junction 35 and theelectronic regenerative repeaterg The sending hub comprises theconnections between the; electronic regenerative repeater and junction.

A potentiometer corresponding to a hub potentiometer, consistingof'resistance. elements 8 and 9 connected between negative battery andground, has its mid-terminal connected to the junction 35 of receivinglegs'l' and 4 and common branch-3.

For the marking condition the'ar'matures of the four relays WRL, ER, WSand ES'are all in engagement with their right-hand Ormarking contacts,as shown. The armatures of the receiving relays WR and ER-are bothactuated to engage their marking contacts due .to the net magneticeffect of the current in their windings; not shown, as well understoodin the art. With the armature of relay WR. on its marking contact, acircuit maybe traced from positive battery through its marking contactand armature, receiving leg I and resistance Into the-junction 35.Similarly with the armature of relay ER in engagement with its markingcontact, a circuit may be traced from positive battery through themarking contact and armatureof relay ER, receiving leg 4 and resistanceH. to junction 35 Under this condition junction 35'andcommon branch 3are at positive potential andtriode '1- conducts. 'The positive anodesupply potential of triode i applied through resistance -26-'-to theanode is reduced for the conducting condition .of triode l and thereduced potential is applied through the branch connnecting junctionsand 38'between the sending legs 2 and 5' and through resistances l3 and[2 respectively to the-grids of the west sending pentode 48 and the eastsending pentode 50 respectively. When the armature of either relay WR.or ER is actuated to eng'age its lefte-handor spacing contact anegative-potential is applied through the respective sending leg tojunction 35 which goes'negative'. The negative potential applied throughthe common branch 3 cuts off triode I which in turn raises the positivepotential applied to junction 38 and to the grids of pentodes 48 and 5B.

It will be assumed that relay WR transmits-"a spacing signal toward thecommon branch 3; A-

circuit may then betraced from'negative battery through the spacingcontact and armature ,of relay WR, junction 36 and resistances l6 and.I'I tonegative battery. The grid of the left-hand triode I4 of thedouble or flip-flop trio'des l4 and I5 is connectedv to the'J'unctio'nbetween resistances I6 and ll.

For this condition triode-14 cuts off. A circuit may be traced from thepositive anode supply battery through resistance I8 to the anode oftriode l4 and from junction 4I through resistances and 22 tonegative'battery. It is assumed for this condition that the eastreceiving relay ER does not attempt to trans-' mit a spacing signalsimultaneously, which would result in an abnormal condition to bediscussed hereinafter.

as shown, therefore, and a circuitfm'ay be traced. from positive batterythrough the marking contact and armature of relay ER, leg" 4, terminal31 and resistances 49 and 22 to negativeb'atteiw.

The grid of triode I5 connected to the junctionot resistances 2B, 49 and22. With triode I4 cut-off, the, potential of junction-4i and the gridoftriode t5 are raised and triode i5 conducts. Alcircuitr-may also betraced from positiveanode supply. battery through resistances I9 and 23to junction 39 in sending leg' 2. With triode I5 con-' ducting; the.potentials of its anode and of junctions 42 and 39 are lowered.Notwithstanding the raised potential of junction-38, dueto theinactivation of triode 7, as explained, the lowered potentialapplied tojunction 39 and the grid of pentode 48 is dominant and pentode 43remains cut off; A positive potential is applied to the screen grids ofeach ofpentodes 48 and 5il through the variable potentiometers 21 and30-respectively to fixtheir output, when activated, ata predeterminedvalue so that thesignals generated by the-sending relays are unbiased.

. With triode 48 cut off, no current flows in a circuit which'maybetraced from positive battery through the top winding of relay WS,resistance '28, and iromthe; anode to the grounded cathodeof pentode 48.The armatureof'relay WS is under theinfluenc'e'of itsbiasing, windingonly in a circuitqfrompositive battery through the biasing winding andresistance 29 togrjound, the, effect of which urges the armature ofrelay WS.-to engage its right-hand or marking contact asshown. r A.circuit 1 may. also, be traced. .from. Junction 1 5 I intheanode'circuit ottriode I4 through resist, ancer24to junction. and thegrid ofpentode 50. -With triode I4 cut off thepotential of the grim-ofpentode 5d raised and since triode" 7 iscutoii andthe'potential ofterminal 38. is: also at-its: higher value,.pentode 5B conducts. Acinuitmay be traced-from positivebattery through the-tonwinding of relay ES,.resistance 31 and from the anode to the cathode of pentode 50.. Theefiect of current in this path through the top winding of relay ES tendsto actuate its armature to engage its spacing contact and this eirect isdominant over the opposite effect of the current flowing from positivebattery throughthe bottom or biasing winding of relay ES and-resistance32 to ground tending to maintain :thezarmature of relay E8 on itsmarking contact and the armature of relay ES will be actuated to engageits-spacing contact to transmit a spacing'signal tothe-distant connectedstation.

When the armature ofrelay WR is again ac-'- tuated to engage its markingcontact, positive battery will be impressed through junction 36 andresistance IE on the grid of triode I4. This will -be-inefiective toactivate triode I4, however, since, .for this condition, with triode I5activated, a dominant more negative potential is impressed tromjunction-43, at the anode of. triode I5, through resistance H on thegridof triode I4, which triode remainsicutaofi during.;the entire Thearmature of relay ER. remains in engagement with its marking contact '4interval while relay WR continues to transmit toward the common branch 3and until relay ER later may start to transmit toward the common branch.Each marking signal transmitted from relay WR will activate triode I andthe reduced potential of junction 38 will be controlling in its effecton pentode 50 notwithstanding the potentials of junctions 5| and 40 areat their higher value as triode I4-is cut oil, so that pentode 50 willbe inactivated-' for each marking signal element andthe armature ofsending relay ES will be restoredtoitsmarking contact.

So in response to spacing and marking signal elements transmitted fromthe armature of relay WR, the armature of relay WS will be maintained onits marking contact, while the armature of relay ESwill beactuatedbetween..;its spacing and marking contacts. p

If now the armature of relay EBgisi actuated to spacing while-thearmature of relay WR.is ..on its marking contact, the negative spacingipotential applied through the spacing contact and armature of relay ER,junction 31, resistance. 49 and junction 45 on the grid of triode I5will be of sufficient magnitude to swing the grid negativenotwithstanding the positive potential impressed from the anode ofinactivated triode I4, atjunc tion 4I through resistance 28 and Junction4.5011 the grid of triode I5 .and triode. I5 will be in.- activated. Araised positive potential will beimpressed through resistance 23 onjunction: 39. Triode I will be out off..forthe spacing-condition. Thepotential .ofjunction 38 will-beraised, Pentode 48 will conduct andrelayWS will trans,- mit a spacing signal to the distant repeaten; S i-.-multaneously a raised positive potentialwill be applied throughresistance 2! on the-grid of triode I 4 which together with the positivepotential applied from the marking contact afrelay WR through.resistance IE on the grid of tri: ode I 4 will activatetriodeI4,-.lowering the potential of junction 5I whichis applied throughresistance 25 on junction 40 and the gridoi pentode 58. This: willcutoff pentode 50. The armature of relay ES will therefore be maintainedin the marking condition and it will thuszbe prevented fromretransmitting the spacing signal received from the east repeater backto the east repeater while the spacing signal'is. propagated to the westrepeaten. I If the armature of relay WR'is in engagement with itsspacing contact in response to the refception of a spacing. signal fromthe distant west repeater and simultaneously. thegdistant .eastrrepeatertransmits a spacing signal to relayER. the armatures of both the WR andER relays will impress negative battery on their respectivereceivinglegs and common branch 3 to ,cut; oil triodei l and raise thepot'entialof junction .38. Negative potential will be impressedalsothrough resistances I6 and 49 on thegridsof triode's i l and I5,respectively, bothof'which will therefore be inactivated. As a result ofthis a raised positive potentialwill be impressed from the anodes'oftriodes I4 and I5 through-resistances 2 4 and 23 respectively on thegridso f' pento'des 50and 48.respectively each of which will be'ailtir'vated, in turnenergi'zing the top windings ofr'e'flays WS and ES, andactuating the armatuitiof each to spacing-to propagate a spacing.s'ignalto' .upon-whether.=the second space-was intended as a break or.was an inadvertency. r Refer nowto Fig. 2 which is. quite similar toFig. 1 except for the omission of the triode T and the addition of adouble triode hold tube i 202 and other minor changes.

=The system-per Fig. 2 is shown in the marking condition. It will beassumed that the relay WR transmits a spacing signal toward the, commonbranch 203. Under this conditionthe cathode of triode 2 I4 is madesufliciently negative that triode 214 is activated. The anode of triode2l4 is connected to the grid of triode 2 l 5 and when triode 214 isactivated triode 2 I5 is cutoff. A raised positive potential istherefore impressed through resistance 223 on the grid of hold. triode20L The negative spacing potential .is impressed through the westreceiving leg, common branch 203, the electronic regenerative repeater,resistance 225 and resistances 255 and 250 in parallel on the cathodesof triodes 201 and 202 respectively. A reduced potential is applied fromthe anode of triode 2 through resistance 224 on the grid of triode 202.Triode 20! is activated and triode 202 is inactivated. The negativespacing potential of the cathode of triode-20! due to the spacingcondition of the common branch 203 is made more positive as a result ofthe conduction of triode 20! and double sending triode 248 conducts.This makes the potential of juncspacing. This makes the grid of triode3i4-of tion 260 positive and the polarized sending, relay WS ismaintained in engagementwith its marking contact by the effect ofcurrent-flowing from positive potential at. junction 280 through thewinding of relay WS to ground. .80 the spacing signal generated by relayWR is not transmitted from relay WS. I s.

Since triode 202 is inactivated no current can flow from its plate toits cathode. The negative potential applied by the regenerative repeaterthroughresistances 225 and 256 on the grids of double sending triode250, the cathodes of which are at a less negative potential, inactivatesdoubletriode 250 and negative potential is impressed through resistance262 and the winding of polar sending relay ES activating its armature tospacing. When the armature of relay WR reengages its marking contactapositive holding potential will continue to be applied. from the anodeof inactivated triode 2 i 5 through resistance 22! to maintain triode 2l5 activated, so relay WS willcontinue to be held on marking while relayWR continues to transmit ,toward common branch 203. Triode 202 ismaintained inactivated but the positive marking potential appliedthrough branch203 and resistance 256 on the grid of double, triode 250activates the triode to, restore the armature of sending relayES tomarking. s

The operation of the. system forv the transmission .of aspacing signalfrom relay ER corresponds to that described for the transmissionof.:a.spacing signal from relay WR.

If both relays WR and ER attempt to transmit a spacingsignal at the sametime. triodes 2M and'2l5 will both be activated, in turn cutting offeach ofrhold triodes 20! and 202 and the double triode send tubes 248and 250 will both be inactivated by the regenerative repeater, thuseffecting the transmission of a spacing signal of resistances 308 and309 interconnected between positive battery and ground, applies positivebattery to junction 335 and common branch 303. Relays WR and ER for themarking condition; as shown, impress negative battery through,- theirrespective sending legs on junction 335 and com-' mon branch 303 whichfor the marking condition is negative. This negative potential isimpressed through resistances 3H and 3l3 on the two grids of each of thewest sending doubletriode 340 and on the east sending double triode 350,respective-1 ly," the two cathodes of each of whichare at a low negativepotential. Starting with the marking condition, if either relaygWR or ER15 .80! tuated to spacing, positive potential is applied through thecorresponding leg and junction 335.

and common branch 303 which tends to chan e the potential applied to thegrids of each of triodes 348 and 350 to positive. a It will be assumedthat relay WR is actuated to the flip-flop triodes 314 and 315morepositive and triode 3|4 is activated while triode 3l5 ,iscut oflf. Areduced potential is applied through resistance 324 on the grid oftriode 302 and a raised poten-i tial is appliedthrough resistance-323 onthe. grid v of triode 30!. Triode 302.cuts 01? and triode 30,1.conducts. A raised potential is applied by the.

regenerative repeater on the grids of doubletriode A lowered potentialis .ap,-

35 0 which conducts. plied from the plate of triode30l on the, grids'ofdouble triode 348 which remains cut off. Junce tion 36 I becomespositive and relay ES is actuated.

to spacing. Junction 360 remains negatiye main-.

taining relay VVS in 'the marking condition.

When relay -WR is restored tothe marking con,- dition. triode 3I4 in theflip-flop circuit remains activated and triode 3l 5 remains cut off sothat the potential conditions applied to the. grids 101 triodes 348 and350 by the hold, triodes remain unchanged. The common branch 303 goesnega--- tive in response to, a marking signal and. this voltage appliedalso to the grids of double triode 350 is dominant so that double triode350 cuts off and the armature of relay ES is restored to. marking. Sincea lowered potential is-applied to the grids of double triode 348 bothfrom .the

common branch and from thehold triode. .301,-

double triode 348 remains cut off and relay WS.

is" maintained on its marking contact. So relay ES follows the markingand, spacing.

signals transmitted from relay WR and relay- WS:

is maintained in-the marking condition. 'When' communication signals aretransmitted from'ree from each of relaysWS and ES to inform of the 0tiometer, resembling a hubpotentiometer, formed lay ER, relay. WSfollows the signals and relay ES is maintained on marking in amannerwhich should-be apparent from the foregoing. ,1

.7 If both relays WR and. ER transmit spacing:

signals simultaneously both flip-flop triodes. 3M and 3E5 conduct. Bothhold triodes 301 and 302 are cut off.--Thepositive'potential'suppliedfrom the output of the regenerativerepeater isefie'ctive on the gridsof both the send tubes. 3'48 and 350.Send tubes-348 and 350 conductand a'positive; potential impressedonjunctions 360 and 36 -1; actuates relays WS and ES respectivelytospacing to transmit a spacing signal from each as an indication of theabnormal condition Whatis claimed is: luln a half-duplex direct-currenttelegraph repeater-system, a first telegraph repeater, a sec-j ondtelegraphlrep eater, a receiving leg'and a"- sending leg inweach .ofsaid repeaters," "a common brancha. regenerative repeater insaid brancmsaid-legs. connecteduito said branchi-Qfii'fl b1 61 afieviteieeraiih-communiceuzi'on signaling: .zpath; extendingzthruugn said receivingleg-i 11: said repeateni through said common 'branchand throughsaid-sending 'legin said second repeater establishable-ata first time,asecond. operable telegraph cdmmunication-signaling' pathextending-through said receiving 'le'g said second re: peaterthroughsaid common branch and-through s'ai'di'sending leg in said firstrepeater establishable at a' second time, a circuit-common to said firstand: to saidseeond repeaters, said control circuit includingspacedischarge devices for blocking said-sending leg of said first repeaterand said 'seriding leg of saidsecond repeater-at said first andsaid-secondtimes respectively, said space discMarge devices comprising:a flip-flop circuit, said-circuit having an individual input connect'ion to each of said receiving legs and an individual output connectionto eachof said sending tes z- K 2;- In a half-duplex telegraph repeatersystem, ar -first telegraph repeater having a receiving leg anti asendingleg connected to a common hub, a second telegraphrepeater havinga receiving leg and a sending leg connected to said hub,and

. a control circuit-serving said two repeaters: in

common, to control communication from the receiving leg 'of eitherrepeater through said hub and throu'gh the sending leg of the othenr'epeater, individualglumped impedances inv each of said sending legs, eachof "said impedances having a first terminal connected individually'tosaid hub, and "an individual communication direction' reg'ulati ngconductor for each ofsaid sending legs extending from a second terminalof said: resistance in each respective" leg to said common controlcircuit.

In a half-duplex direct-current hub telegraph repeater system, a hub, afirst and a second telegraph repeater, each'of said repeaters havingareceiving relay connected through a receiving leg to said hub and asending relay connected through asendingjle'g'l to said hub, acommunication': signal direction control circuit, said control circuitcommon to bothofsaidfrepeaters for controlling transmission from oneto-another of said repeaters; a first and a second space dischargedeviceinsaid control circuit, a connection from said receiving'leg 'ofsaid first repeater tothe input of said first device, a connectionfromsaid receiving'legof said second repeater-to the input of'saidiseconddevice, interconnections between said two devicesforactivating or deactivating-one il'l'IGSDOIlSB' totheactivation ordeactivation of the-other, individual connections from each of said'devices to resp'ective ones of said sending legs andan individuallumped impedance in each" said sending 'leg'between i said individualconnectionsand said hub; a,

l .R'In a direct current half-duplextelegraph system, a firsttelegraphreceiver; a first telegraph 'tran'smittena second telegraph receiver, asecend: telegraph transmitter, a receiving hubl'ia sendingihub,anindividual telegraph leg con-' meeting ,each of said-receivers to saidreceiving hubyanindividualtelegraph leg connecting each oilaidtransmitters tosaid sending hub, a regenerative-repeater interconnectingsaid hubs, a con-' trol circuit for controlling the direction oftransmission of communication signals between said telegraph receiversand transmitters, said con ,trol circuit common to said first and saidsecond transmittersand receivers, said control circuit ineludingv two,space discharge devices" intercon-j nected tqjriorm' a-fiip-flopcircuit, an individual impedance andsaidlspacedischarge device'in itsre'spectivetransmitting leg.

5'. Aisystemflin accordance with claim 4 includ ing a; space dischargedevice in said sending hub; said devicehaving an input connected. tothe-out put of said regenerative repeater and. an output constitutinga"fporti'on'-of said? sending hub. v6. "In? a huh-type telegraphrepeater concentration, two individual hub-type repeaters interconnectedthrough individual receivinglegsland individual sending: legs to a hub,a control circuit corxnncn to said two repeaters for controllingtransmission between" said two repeaters, said control circuithavi'ngtwo space discharge'devices interconnected to'form a. flip-flopcircuit, an input of eac'h' device. connected individually to saidindividual receiving legs, a first and a second hold. discharge device;each: of saidlhold devices having" an input connected. to the output of.individual one-of said: fiipa-fiopdevices, each ofsaid hold deviceshaving an output connected to an individual sendinglegand a lumped 'impedan'ce' in" each; said. sending. leg; intermediate said outputconnection to its respective: hold de vice and said hub. v

7; In "a" half-duplex" direct-current telegraph repeater system; a'iirstirtelegraph' repeater, a second telegraph repeater, a receivingleg and a sending leg in. each of said repeaters, a common branch; atregenerative repeater in said branch, said legs connected to'said'branch,.a first operable telegraph path extending from said'receivingleg-in said firs't'repeater thinughfsaid. common branch andthroughsaidsending legiin said second'repeater establishable at a first time,asecond operabletelegraph path." extending from said;re ceiving' leg 'insaid second repeaterthroughi said common branch and-through saidsending. leg in said first repeater establishable at a second time,accntrol circuit common'to said twoi'repeaters saidlcontrol: circuitincluding: space discharge de--: vices and a firstiresistancenetworkpotentiometer having" first potential connections" thereto for blockingsaid sendingilegoflsaid first repeater and.

" file of this patent? said sending leg 'oiisaid second repeater at saidfirst and said second times respectively for norrnal communication, saidcontrol: circuitrincludi-ng also second potential connections;t'orsaidwpotentiometer for 'unblockin'g' both of said sending legssimultaneousl'yin response to an abnormal condition. i" f WILTONTUREA;

* rinnnanncnsv'orrnn The following references are of record the UNITEDSTATES PzirENrrs Number" Name" Date:

2,337,886? Hanley flsusslpinDecs281-1943-

